Greater New Orleans

Democratic Sen. Mary Landrieu, photographed as she qualified to run for a fourth term, is subject to the 2nd highest number of critical ads by groups that get financial support from the Koch brothers, according to a new report. (Diana Samuels, NOLA.com | The Times-Picayune)

WASHINGTON -- Political advocacy groups financed, at least in part, by conservative billionaires Charles and David Koch, have aired 43,900 television ads aimed at helping Republicans win control of the U.S. Senate, according to a report Thursday from the Center for Public Integrity.

The groups' largest ad buys have been in North Carolina, some 8,600, but Louisiana is a close second, with 4,900 ads, according to the center report based on data provided by advertising tracking service Kantar Media/CMAG.

The Koch brothers, who operate a large industrial business, have helped finance six nonprofit advocacy groups, Americans for Prosperity, the American Energy Alliance, Concerned Veterans for America, Freedom Partners Chamber of Commerce, Generation Opportunity and the 60 Plus Association.

The center said the six groups are responsible for one out of every 10 TV ads in the 2014 battle for control of the Senate, with Republicans hoping to capture the majority from Democrats.

The groups' ads in Louisiana have mostly criticized Sen. Mary Landrieu, D-La, who is seeking a 4th Senate term, for her support of the Affordable Care Act.

One of the key races that can decide whether it whether Majority Leader Harry Reid, D-Nev., will be replaced by Sen. Mitch McConnell, R-Ky., is the Louisiana race in which Landrieu is being challenged by a Republican field led by Rep. Bill Cassidy, R-Baton Rouge, and Tea Party conservative Rob Maness.

In addition to TV ads, Americans for Prosperity, which has been the Koch brothers affiliated group most active in Louisiana, has also sent out mailers. Among them a piece sent to New Orleans area homeowners that says "Mary Landrieu isn't listening to Louisiana," charging that the Affordable Care has resulted in huge increases in the cost of health insurance and let thousands to lose insurance.

Landrieu has argued that the law, though far from perfect, has provided coverage to over 100,000 Louisiana residents, some of whom, because of pre-existing conditions, couldn't previously get affordable coverage. People who lost coverage because their previous plans didn't meet the coverage requirements of the Affordable Care Act, Landrieu said, were given a waiver to continue receiving that coverage. Landrieu said she has also introduced legislation to provide people who had policies cancelled that would allow them to continue to keep the coverage.

A spokesman for Koch industries suggested that some of the advocacy groups, particularly Americans for Prosperity or Freedom Partners, would be better equipped to comment on the report by Center for Public Integrity, a group that lobbies for campaign finance reform. NOLA.com/The Times-Picayune will include any comments those two groups provide.

The six groups mentioned by the center are not required to provide a list of donors, though the Koch Brothers have made little secret that they support the groups with donations, though others do, as well.

The Center for Public Integrity describes itself as a group dedicated to "revealing abuses of power, corruption and betrayal of public trust by powerful public and private institutions, using the tools of investigative journalism."